Journal of Applied Physiology, Vol 40, Issue 3 281-286, Copyright © 1976 by American Physiological Society
Effect of ether on control of rate and depth of breathing in newborn rabbits
B. T. Thach, I. Wyszogrodski and J. Milic-Emili
The effect of ether anesthesia on Hering-Breuer inflation reflexes of
newborn rabbit pups was investigated. Studies were done at a level of
anesthesia at which an apneustic pattern of respiration is seen in
vagotomized animals. The hypothesis that increase in vagal influence on
respiratory frequency is accompanied by increase in influence on
contractile force of the inspiratory muscles was tested. Two aspects of the
Hering-Breuer reflex, breath duration and airway pressure developed with an
elastic load, were evaluated simultaneously. This was done by performing
airway occlusions at FRC--the results expressed as percent slowing on
occlusion and as effective elastance (E'rs). The animals were studied with
and without anesthesia, before and after vagotomy. Anesthesia resulted in a
marked increase in vagal influence on inspiratory duration (34% increase)
and on total breath duration (36% increase). In contrast E'rs was decreased
(20%) after anesthesia whereas passive elastance was slightly increased.
The vagal contribution to E'rs was essentially the same before and after
anesthesia (36-38%). Thus ether anesthesia increases one aspect of the
Hering-Breuer reflex without changing the other. These findings are likely
due to depression of the central nervous system rather than due to
peripheral effects of ether.
